聚晶金刚石钻头切削齿切削岩块过程的有限元模拟

Finite element modelling of rock mass cutting by cutters for PDC drill bits

建立了聚晶金刚石(PDC)钻头切削齿切削岩石过程的有限元模型,模拟了不同形状切削齿不同切削深度下的线性和圆弧切削过程。模拟前确定了切削齿的空间形态、切削速度、切削深度、材料的流变模型、摩擦模型等。模拟结果表明:线性和圆弧切削过程没有本质区别;各类切削齿的切削力波动均为振荡和不均匀的,不存在周期性;采用同一切削齿时不同切削深度下的切削力波动没有类似规律,但切削深度增加会引起波动幅度增大;切削深度为0.5 mm和1.0 mm时,切削参数保持稳定后平均切削力减小,而切削深度为2.0 mm时,进入稳定切削区后平均切削力并未减小;使用球形齿和圆锥形齿时切削力较小,而使用锥形齿、斜角形齿和平板形齿时切削力较大;采用平板形齿时切削力波动图上单位时间内峰数最少,采用球形齿时最多。

A finite element model of the process of polycrystalline diamond compact（PDC） drill bit cutters cutting rocks was built, and the rock linear and circular cutting processes for different shapes of PDC drill bit cutters were simulated. The following initial data was stated before modelling： spatial form of cutter, cutting speed, cutting depth, rheological model of the processed material, and frictional model. Simulation results show that： there is no essential difference between curricular cutting and linear cutting; all the obtained relations of cutting forces were oscillatory and unevenly for all types of cutters; cutting depth increasing causes oscillation amplitude increasing, although no clear relationship between the fluctuations amplitude and the cutting depth is observed for the same cutter; for cutting depth in 0.5 mm and 1.0 mm, the average cutting force decreases when the cutting parameters are stable, while for cutting depth in 2.0 mm, the stable cutting regime is not accompanied by average cutting force decreasing; the cutting forces are smaller for spherical shape cutter and pick-shaped cutter, and bigger for tapered shape cutter and cutters with bevel and flat; the number of peaks per unit time on fluctuation diagram： the minimum value for flat cutter, maximum value for spherical shape cutter.